Núñez-Dominguez R, Van Vleck L D, Cundiff L V
Roman L. Hruska U.S. Meat Animal Research Center, ARS, USDA, Clay Center, NE 68933.
J Anim Sci. 1993 Jun;71(6):1419-28. doi: 10.2527/1993.7161419x.
Records (2,910) of birth (BWT), weaning (WW), and yearling weight (YW) of F1 calves produced in a top-cross experiment involving Angus, Hereford, Pooled Hereford, Charolais, Limousin, Simmental, Gelbvieh, Maine-Anjou, Chianina, Tarentaise, Shorthorn, and Salers bulls mated to Hereford and Angus cows and records (4,592) of WW on three-breed-cross calves out of 986 F1 females of the same breed crosses were used in this study. The purposes were to estimate how much of the EPD of the sires was realized in crossbred calves and to estimate sire breed effects for the traits adjusted for genetic trend and sire sampling. Published EPD for BWT, WW, YW, net maternal ability (MLK), and maternal WW (MAT) were used. Average regressions (kilograms/kilogram +/- SE) of BWT, WW, and YW of F1 calves on EPD of the sire were 1.04 +/- .10, .88 +/- .11, and 1.40 +/- .11, respectively. The regressions (b, kilograms/kilogram) were similar to the expected values of 1.0 except for YW. For WW of three-way-cross calves on MLK EPD of the maternal grandsire, b was 1.02 +/- .11, which was not different from the expected value of 1.0. Estimated sire-breed means were adjusted to a 1982 genetic base by adding b times the difference of the 1982-breed-mean EPD and mean EPD of sires used in the study. Three different adjustments were compared using the b pooled across breeds, a separate b for each breed, and the expected b of 1.0. In general, the adjustments tended to regress breed of sire means toward the average of all breeds, particularly for BWT and WW of F1 calves, and for WW of three-breed crosses. The effect of type of adjustment varied among breeds, but in most cases small differences resulted from using average or expected b. For WW, the range for net maternal effects among breeds was larger than that for direct breed effects.
本研究使用了在一项顶级杂交实验中产生的F1犊牛的出生体重（BWT）、断奶体重（WW）和周岁体重（YW）记录（2910条），该实验涉及安格斯牛、赫里福德牛、混合赫里福德牛、夏洛莱牛、利木赞牛、西门塔尔牛、吉尔维牛、缅因-安茹牛、契安尼娜牛、塔兰泰斯牛、短角牛和萨勒斯牛等公牛与赫里福德牛和安格斯牛母牛进行交配，还使用了986头相同品种杂交的F1代雌性所产三元杂交犊牛的WW记录（4592条）。目的是估计杂种犊牛中父本的预期子代差异（EPD）有多少得以实现，并估计经遗传趋势和父本抽样调整后的性状的父本品种效应。使用了已公布的BWT、WW、YW、净母本能力（MLK）和母本WW（MAT）的EPD。F1犊牛的BWT、WW和YW对父本EPD的平均回归系数（千克/千克±标准误）分别为1.04±0.10、0.88±0.11和1.40±0.11。除YW外，回归系数（b，千克/千克）与预期值1.0相似。对于三元杂交犊牛的WW对母系祖父的MLK EPD，b为1.02±0.11，与预期值1.0无差异。通过加上b乘以1982年品种平均EPD与研究中所用父本平均EPD的差值，将估计的父本品种均值调整到1982年的遗传基础。使用跨品种合并的b、每个品种单独的b以及预期的b = 1.0，比较了三种不同的调整方法。总体而言，这些调整往往使父本品种均值向所有品种的平均值回归，特别是对于F1犊牛的BWT和WW以及三元杂交犊牛的WW。调整类型的影响因品种而异，但在大多数情况下，使用平均b或预期b产生的差异较小。对于WW，品种间净母本效应的范围大于直接品种效应的范围。
